Removal Of Hemicellulose Research Articles

Effects of Different Delignification and Drying Methods on Fiber Properties of Moso Bamboo.

Bamboo has become an important kind of fibrous raw material in the world due to its fast-growing property and abundance of natural fiber. During the purification and utilization of bamboo fiber, the removal of lignin is vital and it is affected by the chemical treatment system and drying method. In this paper, the effects of three different delignification chemical systems and three drying methods (air drying, drying and freeze drying) on the physical and chemical properties of bamboo fiber were comparatively studied. The results prove that all three delignification techniques can effectively remove lignin from wood, and by utilizing peroxyformic acid and alkaline sodium sulfite, hemicellulose can be removed to a certain extent. With the selective removal of amorphous hemicellulose and lignin and the hydrolysis of cellulose molecular chains in amorphous regions, all three treatments contributed to an increase in the relative crystallinity of cellulose (ranging from 55% to 60%). Moreover, it was found that the drying methods exerted a certain influence on the mechanical properties of fiber. For instance, drying or air drying would improve the tensile strength of fiber significantly, approximately 2-3.5 times that of original bamboo fiber, and the tensile strength of the drying group reached 850-890 MPa. In addition, the alkaline sodium sulfite treatment had little effect on the thermal stability of bamboo fiber, resulting in high thermal stability of the prepared samples, and the residual mass reached 25-37%. On the contrary, the acetic acid/hydrogen peroxide method exerted great influence on the thermal stability of bamboo fiber, giving rise to a relatively poor thermal stability of prepared fibers, and the residual mass was only about 15%. Among the three drying methods, samples under air drying treatment had the highest residual mass, while those under freeze drying had the lowest. To summarize, the alkaline sodium sulfite method is more suitable for preparing bamboo fiber with higher tensile strength and thermal stability.

Chemical Composition and Extraction of Micro Crystalline Cellulose from Outer Skin Isolated Coffee Husk

Coffee husk (CH) is a sustainable and abundantly available cellulosic waste material. Its fiber consists of cellulose as the major structural part which leads to potential utilization for the manufacturing of microcrystalline cellulose (MCC) products that can be utilized for different industrial applications. In the present study, chemical composition of outer skin-isolated coffee husk was determined and sequential treatments of various untreated (UT) sample, ethanol—toluene treated sample through dewaxed (DW) treatment, sodium hydroxide (NaOH)—treated sample through alkali (AT) treatment, and sulfuric acid (H2SO4)—treated sample through bleaching (BL) treatment have been carried out. The Micro Crystalline Cellulose (MCC) has been extracted through hydrogen peroxide (H2O2) after BL treatment. The BL treatment for MCC extraction process was conducted without chlorine and additional harsh acid treatment, respectively. The characterization of chemically treated samples was carried out to investigate their morphological, physico-chemistry, and thermal behavior through a scanning electron microscope (SEM), Fourier transform infrared—ray (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), and differential temperature analyzer (DTA). From the chemical composition analysis; the cellulose, hemicellulose, lignin, and extractive content were determined and its values were (52.9%), (12.5%), (24.3%), and (9.4%), respectively. In the morphological examination, the great untreated (UT) fiber sample was greatly reduced into a micro-sized BL sample, revealing that (from FTIR analysis) the lignin and hemicellulose contents were greatly removed during chemical treatments and the presence of a micro crystalline cellulose region with 54.7% yield. Also, the sample AT and BL showed the lowest amorphous region in X-RD due to the removal of hemicellulose and lignin. The highest crystallinity index has been determined for the BL sample, i.e., 89.9%. Additionally, the thermal analysis shows that the AT and BL sample has great thermal stability than other (UT and DW) samples at high temperature. Therefore, the outer skin separated coffee husk was prepared from agricultural waste was subjected to eco-friendly chemical treatments to yield MCC. Thus, the extracted MCC is expected to be reliable for replacing other plant materials for the production of crystalline nanomaterial and reinforcing constituent for the fabrication of bio composite.

Optimization of softwood pretreatment by microwave-assisted deep eutectic solvents at high solids loading

Microwave-assisted deep eutectic solvent (DES) has received attention as an ultrafast pretreatment method in lignocellulose fractionation. This study investigated the improvement of milled softwood mixture (MSM) fractionation with chlorine chloride-formic acid (ChCl:FA) to obtain residues with high glucan retention and purity while removing majority of the lignin and hemicelluloses. At the optimum pretreatment conditions i.e., ChCl:FA (1:4), 140 °C, 14 min, 800 W and 15 % (w/v), 96.2 % hemicellulose removal, 90.1 % delignification and 93.5 % glucan retention were achieved. About 85 % lignin was recovered with a 95 % purity when solid loading was 10–20 % (w/v). This study showed that microwave assisted ChCl:FA pretreatment was a suitable means to fractionate MSM to achieve high quality glucan and lignin at high solid loading.

Efficient separation of cellulose from bamboo by organic alkali

This study focuses on the effective separation of cellulose from bamboo through a two-step process. Several organic alkalies 2-pyrrolidinone, ethylurea, dibutylamine, N-methylformamide and tetramethyl guanidine were used to remove lignin and isolate cellulose from massive bamboo. The results showed that tetramethyl guanidine can effectively remove lignin and hemicellulose while retaining almost all the cellulose in the residual solid. The removal of lignin and hemicellulose achieved 86.0 and 84.0% after heating for 3 h at 150 °C, respectively. Subsequently, the final removal of lignin and hemicellulose increased to 91.5 and 93.8%, respectively, after a simple alkaline H2O2 bleach treatment. Interestingly, the loss of cellulose was very small after two-step treatments, and 96.9% of the component was still retained. The crystallinity increased from 69.8–75.2% in X-ray diffraction graphs due to the removal of lignin and hemicellulose. The Scanning electron microscopy images indicated that the diameter of cellulose bundles decreased from 80–100 µm to about 50 µm after organic alkali treatment, and then the fiber bundle was completely separated into a single long fiber with a diameter of about 10 µm after H2O2 bleaching. The Fourier transform infrared spectroscopy spectra confirmed the high selective removal of lignin and hemicellulose. Two-dimensional 1H-13 C Heteronuclear singular quantum correlation were analyzed to investigate the lignin structure and found that only the signals of –OCH3, Cγ–Hγ in β-O-4’ (Aγ) and β-β’ (Cγ) structures and C5-H5 in guaiacyl (G5) did not disappear after two-step treatment.

Regenerated cellulose films from jute fibers applied in conductive nanocomposites

This work studied the sheet resistance and conductivity of nanocomposite of regenerated cellulose films (RCFs) and silver nanoparticles (AgNPs). The novelty is associated with obtaining conductive nanocomposite films from jute fibers, which can be promising for application in electronic devices. A combination of chemical treatments was conducted to obtain bleached jute cellulose, which was used to obtain RCFs. The fibers were characterized by X-ray diffraction, Fourier-transform infrared (FTIR) spectroscopy and thermal analysis. Nanocomposites films were produced containing 0.070, 0.145 and 0.290% (w/w) of AgNPs, compared to a pure RCF. Further, FTIR, ultraviolet-visible spectroscopy, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and sheet resistance using the van der Pauw were used to characterize the films. The chemical treatments removed lignin and hemicellulose present in the fiber, increased the crystallinity index and increased the thermal stability. Additionally, the treated fibers were more thermally stable than raw jute. The RCF thermal stability was approximately 225 °C. SEM-EDS of the films showed dense structures and a homogeneous AgNPs dispersion. The regenerated cellulose/AgNPs films showed an increase in conductivity in the range of 10 -2 S/cm and decreased transmittance with increasing nanoparticle content, with the 0.290% AgNPs sample being the most conductive. • Chemical treatments allowed the removal of lignin and hemicellulose of jute fibers. • Bleached cellulosic fibers enabled the production of regenerated cellulose films. • Bleached cellulose was dissolved in aqueous NaOH to production of nanocomposite films. • Increase of AgNPs in nanocomposite films increased the conductivity of the samples. • The conductivity of the nanocomposite films was in the range of 10 -2 S/cm.

Visualization of wood cell structure during cellulose purification via high resolution X-ray CT and spectroscopy

Wood is a heterogeneous material with multiple scales. Revealing the three-dimensional structure of wood tissue in multiple dimensions works as a prerequisite for the reorganization, modification and high-value utilization of wood. By adopting high resolution X-ray micro computed tomography (XμCT), the three-dimensional structural changes during cellulose purification were reconstructed. In the meantime, the changing process in the chemical composition of wood cell wall was demonstrated in situ using laser Raman spectroscopy imaging technology. Moreover, cellular changes on a two-dimensional scale were observed by ordinary optical, fluorescence, and polarizing microscopes respectively. XμCT results indicated that the disruption of the cell structure of chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) by purification treatment started between the diameter walls of the tracheids, while that of the poplar (Populus sp.) cell structure started between the vessels or between the vessels and the wood rays. Such kind of disruption in cell structure was more pronounced after the hemicellulose was removed, with adjacent cells scattered and deformed. In the first step of matrix removal, the cell wall got thinner primarily out of lignin removal, while in the process of hemicellulose removal, the cell wall swelled with the lye. The Raman images illustrated that the distribution of purified cellulose in the cell wall was related to the degree of cell disruption. In undeformed cell walls, the cellulose was evenly distributed, whereas in shrunken and deformed cell walls, it was unevenly scattered.

Effect of Processing Time of Steam-Explosion for the Extraction of Cellulose Fibers from Phoenix canariensis Palm Leaves as Potential Renewable Feedstock for Materials.

This paper briefly discusses the utilization of pruning wastes as a lignocellulosic source of cellulose fibers, which could be of potential use in the development of valuable materials such as sustainable textiles and fillers for footwear components including uppers and soles. Phoenix canariensis palm leaves, one of the most common plants found in the local environment of the Alicante region (Spain), was used as a biomass raw material. Determining appropriate processing parameters and their desired range of maximum cellulose extraction states is key to improving yields. Therefore, this study aimed at determining the effect of processing conditions on cellulose extraction by optimizing the hydrothermal process, as a part of overall combined processes involving several steps. Specifically, the time of the steam-explosion stage was varied between 15 and 33 min in order to maximize the cellulose extraction yield. The composition of both the extracted fibers and the resulting by-product solutions generated during the different steps were determined by FTIR and TGA in order to analyze the effectiveness of removing hemicellulose, lignin and extractives as well as the removed substances at each stage for their further valorization. Additionally, the morphology of cellulosic fibers was evaluated by SEM and their crystallinity by XRD. Crystalline cellulose fibers were successfully extracted from pruning biomass wastes, achieving more efficient removal of hemicellulose and lignin when the hydrothermal process was assessed over 25-33 min. This resulted in finer and smoother fibers, but the crystallinity of α-cellulose decreased as the time of steam-explosion increased to 33 min. The characterization of waste solutions generated after the different extraction steps confirmed that the most effective treatments to remove lignin and hemicellulose from the cell wall are alkaline pretreatment and a hydrothermal process.

Designing Approach of Fiber‐Reinforced Polymer Composite by Combination of Fibrillated Olive Pomace and Marble Powder

AbstractThe development of effective methods to utilize industrial and agricultural wastes is crucial from the perspective of a circular economy. Marble powder and olive pomace (OP), byproducts of olive oil production and marble processing, are considered one of the major sources causing severe environmental pollution, especially in Mediterranean countries. Herein, marble powder and OP are aimed to use as fillers in polypropylene (PP)‐based polymer composite. In addition, fractionated OP is further fibrillated by a combination of mechanical grinding and ionic liquid treatment to enhance its performance as a reinforcement. After treatment for 24 h, the particle size decreases from about 2.1 to 1.1 µm, and the lignocellulosic composition also varies due to the partial removal of hemicellulose. Finally, the compounding ratio of polymer composites consisting of PP, marble powder, fibrillated OP, and compatibilizer is optimized using response surface methodology (RSM) to achieve both high mechanical properties and high filler contents. Mechanical properties of polymer composite fabricated with optimum ratio are in excellent agreement with those predicted by RSM. Furthermore, the yield strength and Young's modulus of polymer composite are 33.9 MPa and 1.89 GPa, accordingly, which are higher than those of PP.

The Conformation and Thermal Characteristic Of Different Species Of Bamboo Cellulose

Bamboo is a fast-growing biomaterial indigenous to Asia and Oceania that is also a high-yielding renewable resource. Bamboo, which has mechanical properties similar to wood, may be treated with currently available methods. The purpose of this study was to determine the characteristics chemical and thermal characteristic of three bamboo species of Schizostachyum brachycladum, Bambusa vulgaris, and Bambusa oldhamii. Bamboo cellulose was extracted chemically via dewaxing, delignification, and mercerization. The bamboo cellulose species employed were S. brachycladum, B. vulgaris, and B. oldhamii. The bamboo celluloses were characterised using Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). FT-IR and TGA studies confirmed the chemical treatment’s removal of hemicellulose and lignin. The FT-IR measurement demonstrated an increase in the peak intensity at 1020 cm-1, which corresponds to the vibration of the C-O-C pyranose ring, showing that the yield of isolated cellulose increased following chemical treatment. In a TGA test, bamboo celluloses were found to be thermally stable.

Integrated biorefinery of bamboo for fermentable sugars, native-like lignin, and furfural production by novel deep eutectic solvents treatment

Herein, a novel class of DESs comprising tetramethylammonium chloride/lactic acid (TMAC/LA) and tetramethylammonium bromide/lactic acid (TMAB/LA) was proposed to refine bamboo for cascaded production of cellulose residue, native-like lignin, and hemicellulose-derived sugars under a relatively mild condition (120 °C for 2 h). The cellulose residue showed an outstanding digestibility with approximately 90 % glucose yield, which was ten-fold higher than that of raw bamboo. The efficient conversion was attributed to the open structure and increased porosity caused by the hemicellulose removal (71.24–86.57 %) and delignification (53.27–73.62 %). Lignin recovered from the treatment liquor exhibited the β-O -4′ linkages (86.3–89.3 %) characteristic of native milled wood lignin (MWL). The recovered lignin could be well-suited for phenolic compounds production (yield > 50 %). After lignin extraction, the residual liquor is a suitable reaction substrate and medium for furfural production, reaching a furfural yield of 86.9 %. The novel DESs treatment could offer a cascaded biorefinery for sustainable development. • A novel DESs system was proposed to cascade refine bamboo. • Enzymatic digestibility was significantly increased from 10.0 % to 91.0 %. • DESs lignin exhibited the β-O -4′ linkages (86.3–89.3 %) characteristic of MWL. • More than 50 % of phenolic compounds and 20 % of aromatic hydrocarbons was achieved. • 86.9 % of furfural yield was obtained from the treatment liquor.

Potential application of cellulose nanocrystals obtained from cultivated fibers in Amazon forest

The Amazon fibers, Jute (Corchorus capsularis L.) and Malva/Caesarweed (Urena lobata L.), obtained from Phoenix Amazon Project were scrutinized and the biomass components were quantified according to the TAPPI standards. The cellulose amount from jute and caesarweed was, respectively, around 49% and 41%. Scanning Electron Microscopy (SEM) analysis has evaluated the removal of lignin of the fiber through the micro holes located at holocellulose’s samples and the hemicellulose partial removal through the samples’ fibrillation at alphacellulose’s micrographs. The Fourier Transform Infrared spectroscopy (FTIR) results corroborated the delignification and hemicellulose removal through the alphacellulose obtention process. X-Ray Diffraction (XRD) patterns reiterate type I cellulose for the raw/holo samples, and type II cellulose for the bleached ones, with an increase of the crystallinity index from ~60% to ~85% for the samples. Thermogravimetry (TG) showed that the thermal stability of the samples increased until the bleaching process, and decreased after the cellulose nanocrystals (CNCs) extraction because of the ester sulphate groups insertion. The CNCs were successfully extracted, as can be seen on the Atomic Force Microscopy (AFM) images, and the aspect ratio and specific surface area calculated showed that these CNCs present some potential application in polymers matrices.

Recyclable choline chloride-based deep eutectic solvent pretreatment for accelerated enzymatic digestibility of Triarrhena lutarioriparia

Choline chloride (ChCl) is the most common hydrogen acceptor (HBA) used in deep eutectic solvents (DES) due to its low toxicity and biodegradability. In this study, seven types of ChCl-based DESs were used for the pretreatment of Triarrhena lutarioriparia (TL), and the residues after pretreatment were subjected to enzymatic hydrolysis. Characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transformed infrared (FTIR) spectroscopy were used to determine the physical and chemical properties of TL pretreated with DESs. The results demonstrated that ChCl-oxalic acid dihydrate (molar ratio of 2:1; CO2:1) exhibited a good pretreatment ability among the DESs types examined. The optimal TL pretreatment process with CO2:1 was obtained by uniform design (UD) experiments and comprised a solid-liquid ratio of 1:25, temperature of 110 ℃, and time of 5 h, which achieved an enzymatic digestibility of 83.71 %. Furthermore, the cellulose reservation, hemicelluloses removal, and lignin removal still remained over 86 %, 80 % and 67 %, respectively, after being recycled five times. Overall, the CO2:1 pretreatment process was effective for the component separation and enzymatic hydrolysis of TL and will promote the development of a green biological refinery pretreatment process.

Multimode ultrasound and ternary deep eutectic solvent sequential pretreatments enhanced the enzymatic saccharification of corncob biomass

Corncob (CB) is a valuable agricultural waste in high abundance. It is mainly composed of cellulose, hemicellulose and lignin that link in a complex interlocking matrix. The key to its utilization depends on separating cellulose from lignin and hemicellulose using an environment-friendly and effective pretreatment method to improve glucose yield. The study aimed to investigate the effect of sequential pretreatment of CB with ultrasound (US) in conjunction with ternary deep eutectic solvent (TDES). The US, type and molar ratio of TDES, temperature, and time were optimized. The results showed that under the optimum conditions, US (40 +60 kHz, 60 min) + TDES (ChCl-Gly-LA, 1:1:2, 120 ℃, 3 h), the removal of lignin and hemicellulose were 87.54 % and 67.00 %, respectively, and the recovery of cellulose was 82.18 %. After 72 h of enzymatic hydrolysis , the yield of glucose and xylose were 76.94 % and 41.26 %, respectively. Comparatively, pretreated CB yielded 61.58 % glucose and 26.90 % xylose higher than the untreated. Scanning electron microscopy revealed that the surface of the CB became cracked and rugged. X-ray diffraction showed that the CrI increased significantly from 36 % to 59 %. Fourier transform mid-infrared spectroscopy indicated significant changes in the characteristic functional groups of lignin and hemicellulose. Increases in Tonset, Tendset, Tp, Vmax and decreases in Char at 600 °C all corresponded to increases in thermal stability. These results further confirmed that TDES combined with ultrasonic pretreatment effectively removed lignin and hemicellulose. In conclusion, this approach could greenly and efficiently pretreat CB as a new method for biomass pretreatment. • Double hydrogen bond acceptor (donor) ternary pretreatment DES was studied. • The lignin removal efficiency of ternary DES was higher than binary DES. • TDES containing lactic acid reduced significantly the lignin content. • TDES combined with ultrasonic pretreatment increased lignin removal rate. • TDES combined with ultrasonic pretreatment enhanced sugar yields.

Hemicellulose degradation: An overlooked issue in acidic deep eutectic solvents pretreatment of lignocellulosic biomass

Deep eutectic solvents (DESs) based pretreatment is an emerging approach to overcome recalcitrance of lignocellulosic biomass and improve its processability. Among different DESs, acidic DESs (ADESs) is popular due to its appealing performance in the biomass fractionation. Most studies concerning ADESs pretreatment focused on cellulose digestibility , as well as understanding lignin properties and its valorization potential, but overlooked the fate of hemicellulose , especially its degradation and loss. Here, the importance of preventing hemicellulose degradation and improving its valorization to the economic viability of ADESs pretreatment was highlighted. Major degradation products derived from hemicellulose and its degradation pathway in ADESs pretreatment are discussed. Finally, factors affecting hemicellulose removal and degradation in ADESs are analyzed and strategies to mitigate its degradation are proposed. The aim of this review is to call for attentions and concerted efforts of designing ADESs pretreatment for minimizing hemicellulose loss and improving the economics of associated biorefinery. • ADESs are highly effective in solubilizing hemicellulose. • Hemicellulose experiences degradation and loss in ADESs pretreatment. • Reducing hemicellulose loss is critical to the economics of ADESs pretreatment. • ADESs properties and pretreatment conditions affect hemicellulose degradation. • Hemicellulose valorization reduces its loss and benefits ADESs recycling.

Fenton-reaction-aid selective delignification of lignocellulose by Inonotus obliquus to improve enzymatic saccharification

Aiming at improving the efficiency of recovering sugars from wheat straw by the white rot fungus Inonotus obliquus in solid-state fermentation, two Fenton-reaction-aid systems, i.e., one system containing Fenton reaction pretreatment (FRP) and subsequent Inonotus obliquus culture, one system composed of fungal combined treatment with Fe3O4 nanomaterials (NMs), were developed. FRP and NMs improved the fungal growth and degradation efficiency of wheat straw (WS) by regulating ligninolytic enzyme secretion with manganese peroxidase (MnP) (471.0, 359.8 IU g−1), lignin peroxidase (LiP) (108.0, 48.6 IU g−1), and laccase (Lac) (18.0, 13.4 IU g−1) in the FRP group and NMs group within 15 days. Hemicellulose removal on Day 5 and delignification on Day 10 in FRP group (51.3 % and 20.93 %) and NMs group (40.7 % and 12.60 %) were more severe than the control group (19.2 %, 7.37 %). Sugar yield and conversion rate of 10-day-cultured FRP-WS were 228.4 g kg−1 and 37.2 %, 2.1 and 2.6 times higher than that of 10-day-cultured raw WS. Synergism of Fenton reaction and white-rot fungus quickened fermentation period, promoted degradation selectivity, and then subsequent enzymatic hydrolysis. The Fenton-like system established by NMs and I. obliquus made the synergistic system simpler and represented biocompatible chemistry for developing novel microbial cell factories.

Green Extraction Method of Cellulose Fibers from Oil Palm Empty Fruit Bunches

Oil palm empty fruit bunches (OPEFB) is one of the major biomass wastes produced from palm oil extraction process. Due to high cellulose content in OPEFB, the cellulose fibers in OPEFB can be extracted and utilized in versatile applications as a sustainable process technology development. Among multiple pre-treatment processes, chemical pre-treatment is most efficient for the removal of hemicellulose and lignin in extracting high purity cellulose from lignocellulosic biomass. With the undisputed importance of green technology for the progress of our society, it is vital to engage and leverage on green technology in chemical pre-treatment method for extracting cellulose from OPEFB. The objective of this study is to explore a green extraction method for cellulose from OPEFB using low concentration and eco-friendly chemicals. Fourier transform infrared spectroscopy and field emission scanning electron microscope was used to detect the functional groups and to observe the surface morphology of OPEFB, de-waxed OPEFB fibers, delignified OPEFB fibers, acid hydrolyzed OPEFB fibers, and OPEFB extracted cellulose fibers at different stages in confirming the removal of wax, lignin, and hemicellulose from OPEFB extracted cellulose at the end of the extraction process. Crystallinity index increased from 28% for OPEFB to 72% for the OPEFB extracted cellulose, affirms the degradation of OPEFB’s amorphous structure and transforms into higher crystallinity structure. This work has successfully developed a green extraction method for OPEFB cellulose fibers as part of sustainable process technology which would promote the utilization of lignocellulosic agricultural waste from palm oil industry in various applications.

In-depth investigation of the bioethanol and biogas production from organic and mineral acid pretreated sugarcane bagasse: Comparative and optimization studies

Organic acid pretreatment has generated much interest as one of the high potential methods for promoting enzymatic saccharification of lignocellulosic materials. Organic acids are preferred during pretreatment because they are less hazardous than conventional ones and produce less inhibitory fermentation by-products. In the present study, three organic acids (oxalic acid, citric acid, and acetic acid) and inorganic acid (hydrochloric acid) were studied to produce bioethanol and biogas from sugarcane bagasse. An optimization design (Box–Behnken Design (BBD)) among different optimization designs of response surface methodology (RSM) was considered to determine the pretreatment optimum conditions. On this basis, citric acid (CA)pretreatment resulted in maximum glucose yield (7.93 mg/mL) during saccharification. FTIR analysis of the pretreated samples showed that the structure of lignocellulose was changed in higher proportions for the sample pretreated with an organic acid. An increase in cellulose portion and maximum removal of hemicellulose with lower furan generations was observed in organic acid samples. In this study, the maximum solubilization of hemicellulose in hydrochloric acid was also observed due to the abundance of free H+ ions to catalyze the reaction. The ethanol and biogas yield increased by 1.96 and 1.85-fold for citric acid and oxalic acid pretreated sugarcane bagasse, respectively than untreated samples. The present study concluded that oxalic acid and citric acid pretreatment showed the potential to enhance the yield of bioethanol and biogas, respectively. An organic acid in the pretreatment of lignocellulosic biomass can replace traditional methods of using inorganic acids in biorefineries.

Combinations of mild chemical and bacterial pretreatment for improving enzymatic saccharification of corn stover

Biological pretreatment of lignocellulosic biomass plays an important role for the enzymatic hydrolysis. In this study, a nitrogen-fixing and lignin-degrading strain of bacteria was isolated from an abandoned termite colony. Then, it was identified and named as R. ornithinolytica RS-1. To improve the degradation and enzymatic saccharification in corn stover, we used pretreatment with strain RS-1 to deplete the lignin, combined with a 2.5% mild NaOH pretreatment to further deplete the hemicellulose. After only seven days, lignin was degraded by the bacteria RS-1 with a 19% decrease, while the relative content of cellulose increased with 21%. Furthermore, the corn stover cellulose conversion was up to 48.58% by a two-stage process with 2.5% NaOH pretreatment. Meanwhile, significant lignin and hemicellulose removal were observed. Manganese peroxidase activity was highest on Day 3 with the value 181.0256 U/L and lignin peroxidase activity was highest on Day 5 with the value 37.473 U/L, respectively. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses showed significant chemical structural changes after the combined pretreatment. Therefore, strain RS-1 provided an efficient strategy to enhance the enzymatic hydrolysis efficiency by pretreatment of corn stover.

Structural and Mechanical Properties of Hemp Fibers: Effect of Progressive Removal of Hemicellulose and Lignin

ABSTRACT Hemicellulose and lignin were progressively removed from hemp fiber by hydrolysis. SEM, FTIR, XRD analysis and tensile properties evaluation on technical fibers were carried out to understand the structural and mechanical properties of hemp fibers. Significant influence of hemicellulose and lignin content on tensile properties was verified by ANOVA. The fiber tensile strength and initial modulus were decreased with the extensive removal of hemicellulose, along with a constant increasing of elongation at rupture. Torsion and expansion were observed in hemp fibers. It was suggested that the internal structure destruction and reorganization in the ultimate fiber cells was the main reason for the variation of mechanical properties when hemicellulose was gradually dissolved. On the other hand, fiber individualization was achieved by lignin removal and contributed to the elevation of fiber tensile properties. The elongation at break of the hemp fibers decreased slightly with the removal of lignin. NaClO2 solution treatment affected the fiber cells slightly, but effectively changed the properties of the middle lamella jointing between the ultimate fiber cells. The mechanical properties of the hemp fiber were mainly decided by the shearing between single fibers caused by the plastic-like deformation of the middle lamella.

Influence of Alkali and Silane Treatment on the Physico-Mechanical Properties of Grewia serrulata Fibres

Grewia serrulata fibres were chemically treated with 3%, 6%, and 9% NaOH for the duration of 4 h. Additionally, the NaOH-treated fibres were also treated with 3 – (trimethoxysilyl) propyl methacrylate (silane). Properties such as density and tensile strength of the treated fibres were compared against the untreated fibres. The highest density was obtained in the case of 9% NaOH + silane treated fibres, which was 26.47% higher than untreated fibres, implying effective removal of hemicellulose. Likewise, the highest tensile strength was also obtained in the case of 9% NaOH + silane treated fibres. The increment observed in the tensile strength of the natural fibres was related to the removal of impurities, hemicellulose, and stress-raisers as well as deposition over the fibre surface that smoothed it. These observations were further validated by estimating changes in chemical constituents due to chemical treatment along with characterization techniques such as scanning electron microscopy and thermogravimetric analysis.